<?php

function getAuthImage($text) {
    $im_x = 160;
    $im_y = 40;
    $im = imagecreatetruecolor($im_x, $im_y);
    $text_c = ImageColorAllocate($im, mt_rand(0, 100), mt_rand(0, 100), mt_rand(0, 100));
    $tmpC0 = mt_rand(100, 255);
    $tmpC1 = mt_rand(100, 255);
    $tmpC2 = mt_rand(100, 255);
    $buttum_c = ImageColorAllocate($im, $tmpC0, $tmpC1, $tmpC2);
    imagefill($im, 16, 13, $buttum_c);

    $font = 'airbusspecial.ttf';

    for ($i = 0; $i < strlen($text); $i++) {
        $tmp = substr($text, $i, 1);
        $array = array(-1, 1);
        $p = array_rand($array);
        $an = $array[$p] * mt_rand(1, 10); //角度
        $size = 28;
        imagettftext($im, $size, $an, 15 + $i * $size, 35, $text_c, $font, $tmp);
    }


    $distortion_im = imagecreatetruecolor($im_x, $im_y);

    imagefill($distortion_im, 16, 13, $buttum_c);
    for ($i = 0; $i < $im_x; $i++) {
        for ($j = 0; $j < $im_y; $j++) {
            $rgb = imagecolorat($im, $i, $j);
            if ((int) ($i + 20 + sin($j / $im_y * 2 * M_PI) * 10) <= imagesx($distortion_im) && (int) ($i + 20 + sin($j / $im_y * 2 * M_PI) * 10) >= 0) {
                imagesetpixel($distortion_im, (int) ($i + 10 + sin($j / $im_y * 2 * M_PI - M_PI * 0.1) * 4), $j, $rgb);
            }
        }
    }
    //加入干扰象素;
    $count = 160; //干扰像素的数量
    for ($i = 0; $i < $count; $i++) {
        $randcolor = ImageColorallocate($distortion_im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
        imagesetpixel($distortion_im, mt_rand() % $im_x, mt_rand() % $im_y, $randcolor);
    }

    $rand = mt_rand(5, 30);
    $rand1 = mt_rand(15, 25);
    $rand2 = mt_rand(5, 10);
    for ($yy = $rand; $yy <= +$rand + 2; $yy++) {
        for ($px = -80; $px <= 80; $px = $px + 0.1) {
            $x = $px / $rand1;
            if ($x != 0) {
                $y = sin($x);
            }
            $py = $y * $rand2;

            imagesetpixel($distortion_im, $px + 80, $py + $yy, $text_c);
        }
    }

    //设置文件头;
    Header("Content-type: image/JPEG");

    //以PNG格式将图像输出到浏览器或文件;
    ImagePNG($distortion_im);

    //销毁一图像,释放与image关联的内存;
    ImageDestroy($distortion_im);
    ImageDestroy($im);
}

function make_rand($length = "32") {//验证码文字生成函数
    $str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    $result = "";
    for ($i = 0; $i < $length; $i++) {
        $num[$i] = rand(0, 25);
        $result.=$str[$num[$i]];
    }
    return $result;
}

//输出调用
$checkcode = make_rand(4);
session_start(); //将随机数存入session中
$_SESSION['helloweba_gg'] = strtolower($checkcode);
getAuthImage($checkcode);
?>
